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Abstract:

An optical system is able to achieve a substantially azimuthal
polarization state in a lens aperture while suppressing loss of light
quantity, based on a simple configuration. The optical system of the
present invention is provided with a birefringent element for achieving a
substantially circumferential distribution or a substantially radial
distribution as a fast axis distribution in a lens aperture, and an
optical rotator located behind the birefringent element and adapted to
rotate a polarization state in the lens aperture. The birefringent
element has an optically transparent member which is made of a uniaxial
crystal material and a crystallographic axis of which is arranged
substantially in parallel with an optical axis of the optical system. A
light beam of substantially spherical waves in a substantially circular
polarization state is incident to the optically transparent member.

Claims:

1. A device fabrication method comprising:preparing a photosensitive
substrate; andexposing a pattern to be transferred, on the photosensitive
substrate through an optical system;wherein the optical system comprises
a birefringent element, an optical rotator, and an optical member
including a predetermined power, andwherein the exposing comprises making
a beam bundle including passed through the birefringent element, pass in
order through the optical member including the predetermined power and
through the optical rotator.

2. The device fabrication method according to claim 1,wherein the optical
system includes an illumination optical system, andwherein the exposing
includes an illumination step for illuminating the predetermined pattern
through the optical system.

3. The device fabrication method according to claim 2,wherein the
birefringent element is located near the predetermined pattern surface,
or at or near a position optically conjugate with the predetermined
pattern surface, in an optical path of the illumination optical system,
andwherein the illuminating includes establishing the position optically
conjugate with the predetermined pattern surface, by the optical member
including the predetermined power.

4. The device fabrication method according to claim 3,wherein the
birefringent element is located at or near the position optically
conjugate with the predetermined pattern surface, in the optical path of
the illumination optical system, andwherein the establishing the position
optically conjugate with the predetermined pattern surface comprises
making a beam bundle pass through the optical rotator.

5. The device fabrication method according to claim 3,wherein the
illuminating comprises forming a secondary light source including a
predetermined optical intensity distribution, on an illumination pupil
plane, andwherein the predetermined optical intensity distribution of the
secondary light source is so set that an optical intensity in a pupil
center region being a region on the illumination pupil and including an
optical axis is smaller than an optical intensity in a region around the
pupil center region.

6. The device fabrication method according to claim 5,wherein the
predetermined optical intensity distribution of the secondary light
source includes an optical intensity distribution of an annular shape or
multi-pole shape.

7. The device fabrication method according to claim 3,wherein the
birefringent element is located at or near the position optically
conjugate with the predetermined pattern surface, in the optical path of
the illumination optical system,wherein the illuminating comprises
guiding a beam bundle from an optical integrator to the predetermined
pattern surface, andwherein the beam bundle including passed through the
optical integrator is incident to the optical rotator.

8. The device fabrication method according to claim 1,wherein the optical
system includes a projection optical system, andwherein the exposing
includes forming an image of the predetermined pattern on a surface of
the photosensitive substrate through a liquid.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This is a Divisional of U.S. patent application Ser. No. 10/587,254
filed on Jun. 1, 2007, which is hereby incorporated by reference in its
entirety. This application is based upon and claims the benefit of
priorities from International Application No. PCT/JP2005/000406 filed on
Jan. 14, 2005, Japanese Patent Application No. 2004-018226 filed on Jan.
27, 2004, and Japanese Patent Application No. 2004-338749 filed on Nov.
24, 2004 the entire contents of which are incorporated herein by
reference.

BACKGROUND

[0002]1. Field

[0003]One embodiment of the present invention relates to an optical
system, exposure apparatus, and exposure method and, more particularly,
to an exposure apparatus for fabricating micro devices, such as
semiconductor elements, image pickup devices, liquid-crystal display
devices, and thin-film magnetic heads, for example, by lithography.

[0004]2. Description of the Related Art

[0005]In the typical exposure apparatus of this type, a light beam emitted
from a light source is guided through a fly's eye lens as an optical
integrator to form a secondary light source as a substantive surface
illuminant consisting of a lot of light sources. A light beam from the
secondary light source is guided through an aperture stop disposed in the
vicinity of the rear focal plane of the fly's eye lens, to be limited,
and then is incident to a condenser lens.

[0006]The light beam condensed by the condenser lens illuminates a mask
with a predetermined pattern therein, in a superposed manner. Light
transmitted by the pattern of the mask travels through a projection
optical system to be focused on a wafer. In this manner the mask pattern
is projected (or transferred) onto the wafer to effect exposure thereof.
The pattern formed in the mask is of high integration and a high-contrast
pattern image must be formed on the wafer in order to accurately transfer
the microscopic pattern onto the wafer.

[0007]Japanese Patent Application Laid-Open No. 5-90128 proposed
technology of obtaining the high-contrast image of the microscopic
pattern on the wafer, for example, by setting a polarization state of
exposure light to linear polarization of circumferential vibration
(hereinafter referred to as "azimuthal (circumferential) polarization
state") in a lens aperture (pupil plane) of the projection optical
system.

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

SUMMARY

[0008]An embodiment of the present invention provides an optical system
capable of achieving a substantially azimuthal polarization state in the
lens aperture while suppressing the loss of light quantity, based on a
simple configuration. Another embodiment of the present invention
provides an exposure apparatus and exposure method capable of forming a
high-contrast image of a microscopic pattern of a mask on a
photosensitive substrate to effect high-throughput and faithful exposure,
using an optical system capable of achieving a substantially azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity.

[0009]For purposes of summarizing the invention, certain aspects,
advantages, and novel features of the invention have been described
herein. It is to be understood that not necessarily all such advantages
may be achieved in accordance with any particular embodiment of the
invention. Thus, the invention may be embodied or carried out in a manner
that achieves or optimizes one advantage or group of advantages as taught
herein without necessary achieving other advantages as may be taught or
suggested herein.

[0010]The optical system in accordance with an embodiment of the present
invention is an optical system comprising a birefringent element for
achieving a substantially circumferential distribution or a substantially
radial distribution as a fast axis distribution in a lens aperture; and
an optical rotator disposed behind the birefringent element and adapted
to rotate a polarization state in the lens aperture.

[0011]The optical system in accordance with another embodiment of the
present invention is an optical system comprising:

[0012]a birefringent optical rotator which is made of an optical material
with linear birefringence and optical rotatory power and an optic axis of
which is arranged substantially in parallel with an optical axis of the
optical system,

[0013]wherein a light beam in a substantially circular polarization state
is incident to the birefringent optical rotator.

[0014]The exposure apparatus in accordance with an embodiment of the
present invention is an exposure apparatus comprising the optical system
of the one of the embodiments, wherein a pattern of a mask is projected
through the optical system onto a photosensitive substrate to effect
exposure thereof.

[0015]The exposure method in accordance with an embodiment of the present
invention is an exposure method of projecting a pattern formed in a mask,
through the optical system of one of the embodiments onto a
photosensitive substrate to effect exposure thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a drawing schematically showing a configuration of an
exposure apparatus according to an embodiment of the present invention.

[0017]FIG. 2 is a drawing for explaining an action of a conical axicon
system on an annular secondary light source.

[0018]FIG. 3 is a drawing for explaining an action of a zoom lens on an
annular secondary light source.

[0019]FIG. 4 is a perspective view schematically showing an internal
configuration of a polarization monitor in FIG. 1.

[0020]FIG. 5 is a drawing schematically showing a major configuration of
an exposure apparatus according to an embodiment of the present
invention, to show a configuration from a mask blind to a wafer.

[0021]FIG. 6 shows (a) a linear polarization state of circumferential
vibration in a lens aperture, and (b) a linear polarization state of
radial vibration in a lens aperture.

[0022]FIG. 7 is a drawing showing a state in which a birefringent element
and an optical rotator are provided at predetermined positions in an
optical path of an optical system telecentric on the object side.

[0024]FIG. 9 is a drawing showing a polarization distribution in a lens
aperture of circularly polarized light incident to a birefringent
element.

[0025]FIG. 10 is a drawing showing polarization distributions in a lens
aperture of a light beam having passed through a birefringent element.

[0026]FIG. 11 is a drawing showing a polarization distribution in a lens
aperture obtained through a birefringent element and an optical rotator.

[0027]FIG. 12 is a drawing schematically showing a major configuration of
an exposure apparatus according to a first modification example of the
embodiment of the present invention.

[0028]FIG. 13 is a drawing schematically showing a major configuration of
an exposure apparatus according to a second modification example of the
embodiment of the present invention.

[0029]FIG. 14 is a drawing schematically showing a major configuration of
an exposure apparatus according to a third modification example of the
embodiment of the present invention.

[0030]FIG. 15 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fourth modification example of the
embodiment of the present invention.

[0031]FIG. 16 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fifth modification example of the
embodiment of the present invention.

[0032]FIG. 17 is a drawing schematically showing a major configuration of
an exposure apparatus according to a sixth modification example of the
embodiment of the present invention.

[0033]FIG. 18 is a drawing for explaining change of polarization states in
a birefringent optical rotator with the Poincare sphere.

[0034]FIG. 19 is a drawing schematically showing a major configuration of
an exposure apparatus according to a seventh modification example of the
embodiment of the present invention.

[0035]FIG. 20 is a drawing schematically showing a major configuration of
an exposure apparatus according to an eighth modification example of the
embodiment of the present invention.

[0036]FIG. 21 is a drawing schematically showing a major configuration of
an exposure apparatus according to a ninth modification example of the
embodiment of the present invention.

[0037]FIG. 22 is a drawing schematically showing a major configuration of
an exposure apparatus according to a tenth modification example of the
embodiment of the present invention.

[0038]FIG. 23 is a drawing schematically showing a major configuration of
an exposure apparatus according to an eleventh modification example of
the embodiment of the present invention.

[0039]FIG. 24 is a drawing schematically showing a major configuration of
an exposure apparatus according to a twelfth modification example of the
embodiment of the present invention.

[0040]FIG. 25 is a drawing schematically showing a major configuration of
an exposure apparatus according to a thirteenth modification example of
the embodiment of the present invention.

[0041]FIG. 26 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fourteenth modification example of
the embodiment of the present invention.

[0042]FIG. 27 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fifteenth modification example of
the embodiment of the present invention.

[0043]FIG. 28 is a flowchart of a technique of fabricating semiconductor
devices as micro devices.

[0044]FIG. 29 is a flowchart of a technique of fabricating a
liquid-crystal display element as a micro device.

DESCRIPTION OF THE EMBODIMENTS

[0045]Embodiments of the present invention will be described based on the
accompanying drawings. FIG. 1 is a drawing schematically showing a
configuration of an exposure apparatus according to an embodiment of the
present invention. In FIG. 1, the Z-axis is set along a direction of a
normal to a wafer W being a photosensitive substrate, the Y-axis along a
direction parallel to the plane of FIG. 1 in the plane of the wafer W,
and the X-axis along a direction normal to the plane of FIG. 1 in the
plane of the wafer W. With reference to FIG. 1, the exposure apparatus of
the present embodiment is provided with a light source 1 for supplying
exposure light (illumination light).

[0046]The light source 1 can be, for example, a KrF excimer laser light
source for supplying light of wavelength of 248 nm or an ArF excimer
laser light source for supplying light of wavelength of 193 nm. A nearly
parallel light beam emitted along the Z-direction from the light source 1
has a rectangular cross section extending oblongly along the X-direction,
and is incident to a beam expander 2 consisting of a pair of lenses 2a
and 2b. The lenses 2a and 2b have a negative refracting power and a
positive refracting power, respectively, in the plane of FIG. 1 (YZ
plane). Therefore, the light beam incident to the beam expander 2 is
expanded in the plane of FIG. 1 to be shaped into a light beam having a
cross section of a predetermined rectangular shape.

[0047]The nearly parallel light beam having passed through the beam
expander 2 as a shaping optical system is deflected into the Y-direction
by a bending mirror 3, then travels through a quarter-wave plate 4a, a
half-wave plate 4b, a depolarizer (depolarizing element) 4c, and a
diffractive optical element 5 for annular illumination, and then is
incident to an afocal lens 6. The quarter-wave plate 4a, half-wave plate
4b, and depolarizer 4c herein constitute a polarization state converter
4, as described later. The afocal lens 6 is an afocal system (afocal
optical system) the front focal point of which agrees approximately with
the position of the diffractive optical element 5 and the rear focal
point of which agrees approximately with a position of a predetermined
plane 7 indicated by a dashed line in the drawing.

[0048]In general, a diffractive optical element is constructed by forming
steps with a pitch approximately equal to the wavelength of exposure
light (illumination light), in a substrate, and has an action to diffract
an incident beam into desired angles. Specifically, the diffractive
optical element 5 for annular illumination has the following function:
when a parallel light beam having a rectangular cross section is incident
thereto, it forms an optical intensity distribution of an annular shape
in its far field (or Fraunhofer diffraction region).

[0049]Therefore, the nearly parallel light beam incident to the
diffractive optical element 5 as a light beam converter forms an optical
intensity distribution of an annular shape on the pupil plane of the
afocal lens 6 and then emerges as a nearly parallel light beam from the
afocal lens 6. A conical axicon system 8 is located at or near the pupil
plane in an optical path between front lens unit 6a and rear lens unit 6b
of the afocal lens 6, and its detailed configuration and action will be
described later. For simplifying the description, the basic configuration
and action will be described below in disregard for the action of conical
axicon system 8.

[0050]The light beam having passed through the afocal lens 6 travels
through a zoom lens 9 for variation of a-value and then is incident to a
micro fly's eye lens (or fly's eye lens) 10 as an optical integrator. The
micro fly's eye lens 10 is an optical element consisting of a lot of
microlenses with a positive refracting power arranged vertically and
horizontally and densely. In general, a micro fly's eye lens is
constructed, for example, by etching a plane-parallel plate so as to form
a microlens group.

[0051]It is noted herein that each microlens forming the micro fly's eye
lens is smaller than each lens element forming a fly's eye lens. The
micro fly's eye lens is one in which a lot of microlenses (micro
refracting surfaces) are integrally formed without being isolated from
each other, different from the fly's eye lens consisting of lens elements
isolated from each other. However, the micro fly's eye lens is also an
optical integrator of the same wavefront splitting type as the fly's eye
lens in term of the vertical and horizontal arrangement of the lens
elements with the positive refracting power.

[0052]The position of the predetermined plane 7 is defined near the front
focal position of the zoom lens 9 and the incidence surface of the micro
fly's eye lens 10 is defined near the rear focal position of the zoom
lens 9. In other words, the zoom lens 9 keeps the predetermined plane 7
and the incidence surface of the micro fly's eye lens 10 substantially in
the relation of Fourier transform and, consequently, keeps the pupil
plane of the afocal lens 6 optically nearly conjugate with the incidence
surface of the micro fly's eye lens 10.

[0053]Therefore, for example, an illumination field of an annular shape
around the optical axis AX, similar to that on the pupil plane of the
afocal lens 6, is formed on the incidence surface of the micro fly's eye
lens 10. The entire shape of this annular illumination field similarly
varies depending upon the focal length of the zoom lens 9. Each microlens
forming the micro fly's eye lens 10 has a rectangular cross section
similar to a shape of an illumination field to be formed on a mask M
(i.e., eventually, a shape of an exposure region to be formed on a wafer
W).

[0054]The light beam incident to the micro fly's eye lens 10 is
two-dimensionally split by a lot of microlenses to form a secondary light
source having an optical intensity distribution approximately equal to
the illumination field formed by the incident light beam, i.e., a
secondary light source of a substantive surface illuminant of an annular
shape around the optical axis AX, on the rear focal plane (consequently,
on the illumination pupil). A light beam from the secondary light source
formed on the rear focal plane of the micro fly's eye lens 10 travels
through beam splitter 11a and condenser optical system 12 to illuminate a
mask blind 13 in a superposed manner.

[0055]In this manner, an illumination field of a rectangular shape
according to the shape and the focal length of each microlens forming the
micro fly's eye lens 10 is formed on the mask blind 13 as an illumination
field stop. An internal configuration and action of a polarization
monitor 11 incorporating the beam splitter 11a will be described later. A
light beam having passed through an aperture (light transmitting part) of
a rectangular shape of the mask blind 13 is subjected to focusing action
of an imaging optical system 14 and thereafter illuminates the mask M
with a predetermined pattern therein, in a superposed and approximately
telecentric manner.

[0056]Namely, the imaging optical system 14 forms an image of the
rectangular aperture of the mask blind 13 on the mask M. A light beam
having passed through the pattern of the mask M then travels through a
projection optical system PL which is approximately telecentric both on
the object side and on the image side, to form an image of the mask
pattern on a wafer W being a photosensitive substrate. While the wafer W
is two-dimensionally driven and controlled in the plane (XY plane)
perpendicular to the optical axis AX of the projection optical system PL,
one-shot exposure or scan exposure is effected so that the pattern of the
mask M sequentially exposed into each of exposure regions on the wafer W.

[0057]In the polarization state converter 4, the quarter-wave plate 4a is
arranged so that the crystallographic axis thereof is rotatable around
the optical axis AX, and converts incident light of elliptic polarization
into light of linear polarization. The half-wave plate 4b is arranged so
that the crystallographic axis thereof is rotatable around the optical
axis AX, and changes the plane of polarization of incident linearly
polarized light. The depolarizer 4c is composed of a rock crystal prism
of wedge shape (not shown) and a silica prism of wedge shape (not shown)
having complementary shapes. The rock crystal prism and the silica prism
are constructed as an integral prism assembly so as to be freely inserted
into or retracted from the illumination optical path.

[0058]Where the light source 1 is a KrF excimer laser light source or an
ArF excimer laser light source, light emitted from these light sources
typically has the degree of polarization of not less than 95% and nearly
linearly polarized light is incident to the quarter-wave plate 4a.
However, if a right-angle prism is interposed as a back reflector in the
optical path between the light source 1 and the polarization state
converter 4, total reflection in the right-angle prism will convert
linear polarization into elliptic polarization unless the plane of
polarization of the incident linearly polarized light coincides with the
p-polarization plane or s-polarization plane.

[0059]In the polarization state converter 4, for example, even if light of
elliptic polarization is incident because of the total reflection in the
right-angle prism, it will be converted into light of linear polarization
by the action of the quarter-wave plate 4a and the linearly polarized
light will be incident to the half-wave plate 4b. When the
crystallographic axis of the half-wave plate 4b is set at an angle of
0° or 90° relative to the plane of polarization of incident
linearly polarized light, the light of linear polarization incident to
the half-wave plate 4b passes directly without change in the plane of
polarization.

[0060]When the crystallographic axis of the half-wave plate 4b is set at
an angle of 45° relative to the plane of polarization of incident
linearly polarized light, the light of linear polarization incident to
the half-wave plate 4b is converted into light of linear polarization
with the plane of polarization changed by 90°. Furthermore, when
the crystallographic axis of the rock crystal prism of the depolarizer 4c
is set at an angle of 45° relative to the plane of polarization of
incident linearly polarized light, the light of linear polarization
incident to the rock crystal prism is converted (or depolarized) into
light in an unpolarized state.

[0061]The polarization state converter 4 is arranged so that the
crystallographic axis of the rock crystal prism makes the angle of
45° relative to the plane of polarization of incident linearly
polarized light when the depolarizer 4c is positioned in the illumination
optical path. Incidentally, if the crystallographic axis of the rock
crystal prism is set at an angle of 0° or 90° relative to
the plane of polarization of incident linearly polarized light, the light
of linear polarization incident to the rock crystal prism will pass
directly without change in the plane of polarization. When the
crystallographic axis of the half-wave plate 4b is set at an angle of
22.5° relative to the plane of polarization of incident linearly
polarized light, the light of linear polarization incident to the
half-wave plate 4b is converted into light in an unpolarized state
including a linear polarization component passing without change in the
plane of polarization, and a linear polarization component with the plane
of polarization changed by 90°.

[0062]In the polarization state converter 4, as described above, the light
of linear polarization is incident to the half-wave plate 4b, and let us
assume herein that light of linear polarization with the polarization
direction (the direction of the electric field) along the Z-direction in
FIG. 1 (which will be referred to hereinafter as "Z-directional
polarization") is incident to the half-wave plate 4b, for simplification
of the description hereinafter. When the depolarizer 4c is positioned in
the illumination optical path and when the crystallographic axis of the
half-wave plate 4b is set at the angle of 0° or 90°
relative to the plane of polarization (direction of polarization) of
incident Z-directionally polarized light, the light of Z-directional
polarization incident to the half-wave plate 4b passes as Z-directionally
polarized light without change in the plane of polarization and then is
incident to the rock crystal prism of the depolarizer 4c. Since the
crystallographic axis of the rock crystal prism is set at the angle of
45° relative to the plane of polarization of the incident
Z-directionally polarized light, the light of Z-directional polarization
incident to the rock crystal prism is converted into light in an
unpolarized state.

[0063]The light depolarized through the rock crystal prism travels through
the silica prism as a compensator for compensating the traveling
direction of light, and is then incident in an unpolarized state, into
the diffractive optical element 5. On the other hand, when the
crystallographic axis of the half-wave plate 4b is set at the angle of
45° relative to the plane of polarization of the incident
Z-directionally polarized light, the light of Z-directional polarization
incident to the half-wave plate 4b is converted into light with the plane
of polarization changed by 90°, i.e., light of linear polarization
having the direction of polarization (direction of the electric field)
along the X-direction in FIG. 1 (which will be referred to hereinafter as
"X-directional polarization") to be incident to the rock crystal prism of
the depolarizer 4c. Since the crystallographic axis of the rock crystal
prism is also set at the angle of 45° relative to the plane of
polarization of the incident X-directionally polarized light, the light
of the X-directional polarization incident to the rock crystal prism is
converted into light in an unpolarized state to travel through the silica
prism and then to be incident in an unpolarized state to the diffractive
optical element 5.

[0064]In contrast to it, when the depolarizer 4c is retracted from the
illumination optical path and when the crystallographic axis of the
half-wave plate 4b is set at the angle of 0° or 90°
relative to the plane of polarization of the incident Z-directionally
polarized light, the light of Z-directional polarization incident to the
half-wave plate 4b passes as Z-directionally polarized light without
change in the plane of polarization, and is incident in a Z-directional
polarization state to the diffractive optical element 5. On the other
hand, when the crystallographic axis of the half-wave plate 4b is set at
the angle of 45° relative to the plane of polarization of the
incident Z-directionally polarized light, the light of Z-directional
polarization incident to the half-wave plate 4b is converted into light
of X-directional polarization with the plane of polarization changed by
90°, and is incident in an X-directional polarization state to the
diffractive optical element 5.

[0065]As described above, the polarization state converter 4 is able to
make the light in an unpolarized state incident to the diffractive
optical element 5 when the depolarizer 4c is inserted and positioned in
the illumination optical path. It is also able to make the light in a
Z-directional polarization state incident to the diffractive optical
element 5 when the depolarizer 4c is retracted from the illumination
optical path and when the crystallographic axis of the half-wave plate 4b
is set at the angel of 0° or 90° relative to the plane of
polarization of the incident Z-directionally polarized light.
Furthermore, it is also able to make the light in an X-directional
polarization state incident to the diffractive optical element 5 when the
depolarizer 4c is retracted from the illumination optical path and when
the crystallographic axis of the half-wave plate 4b is set at the angel
of 45° relative to the plane of polarization of the incident
Z-directionally polarized light.

[0066]In other words, the polarization state converter 4 is able to switch
the polarization state of incident light to the diffractive optical
element 5 (consequently, the polarization state of light to illuminate
the mask M and wafer W) between a linear polarization state and an
unpolarized state and, in the case of the linear polarization state, it
is able to switch the polarization of incident light between polarization
states orthogonal to each other (i.e., between Z-directional polarization
and X-directional polarization), through the action of the polarization
state converter consisting of the quarter-wave plate 4a, half-wave plate
4b, and depolarizer 4c.

[0067]Furthermore, the polarization state converter 4 is able to make
light in a circular polarization state incident to the diffractive
optical element 5 (consequently, to after-described birefringent element
21) when the half-wave plate 4b and depolarizer 4c both are retracted
from the illumination optical path and when the crystallographic axis of
the quarter-wave plate 4a is set at a predetermined angle relative to
incident elliptically polarized light.

[0068]The conical axicon system 8 is composed of a first prism member 8a a
plane of which faces the light source side and a refracting surface of a
concave conical shape of which faces the mask side, and a second prism
member 8b a plane of which faces the mask side and a refracting surface
of a convex conical shape of which faces the light source side, in order
from the light source side. Then the refracting surface of the concave
conical shape of the first prism member 8a and the refracting surface of
the convex conical shape of the second prism member 8b are formed in such
complementary shapes as to be able to butt each other. At least one of
the first prism member 8a and the second prism member 8b is arranged
movable along the optical axis AX to vary the distance between the
refracting surface of the concave conical shape of the first prism member
8a and the refracting surface of the convex conical shape of the second
prism member 8b.

[0069]In a state in which the refracting surface of the concave conical
shape of the first prism member 8a butts against the refracting surface
of the convex conical shape of the second prism member 8b, the conical
axicon system 8 functions as a plane-parallel plate and has no effect on
the secondary light source of annular shape formed. However, when the
refracting surface of the concave conical shape of the first prism member
8a is located apart from the refracting surface of the convex conical
shape of the second prism member 8b, the conical axicon system 8
functions as a so-called beam expander. Therefore, the angle of the
incident light beam to the predetermined plane 7 varies with change in
the distance of the conical axicon system 8.

[0070]FIG. 2 is a drawing for explaining the action of the conical axicon
system on a secondary light source of annular shape. With reference to
FIG. 2, a secondary light source 30a of the smallest annular shape formed
in a state in which the distance of the conical axicon system 8 is zero
and in which the focal length of the zoom lens 9 is set to a minimum
(hereinafter referred to as "standard state") is changed into a secondary
light source 30b of an annular shape with the outside diameter and inside
diameter both increased, without change in the width thereof (half of the
difference between the outside diameter and inside diameter: indicated by
arrows in the drawing) when the distance of the conical axicon system 8
is increased from zero to a predetermined value. In other words, the
annular ratio (inside diameter/outside diameter) and size (outside
diameter) of the secondary light source both vary without change in the
width of the annular secondary light source, through the action of the
conical axicon system 8.

[0071]FIG. 3 is a drawing for explaining the action of the zoom lens on
the secondary light source of annular shape. With reference to FIG. 3,
the secondary light source 30a of the annular shape formed in the
standard state is changed into a secondary light source 30c of an annular
shape the entire shape of which is expanded into a similar shape, when
the focal length of the zoom lens 9 is increased from a minimum value to
a predetermined value. In other words, the width and size (outside
diameter) of the secondary light source both vary, without change in the
annular ratio of the annular secondary light source, through the action
of the zoom lens 9.

[0072]FIG. 4 is a perspective view schematically showing an internal
configuration of the polarization monitor in FIG. 1. With reference to
FIG. 4, the polarization monitor 11 is provided with the first beam
splitter 11a located in the optical path between the micro fly's eye lens
10 and the condenser optical system 12. The first beam splitter 11a has,
for example, a form of a non-coated plane-parallel plate (i.e., raw
glass) made of a silica glass, and has a function of extracting reflected
light in a polarization state different from a polarization state of
incident light, from the optical path.

[0073]The light extracted from the optical path by the first beam splitter
11a is incident to a second beam splitter 11b. The second beam splitter
11b, similar to the first beam splitter 11a, has a form of a non-coated
plane-parallel plate made of a silica glass, for example, and has a
function of generating reflected light in a polarization state different
from a polarization state of incident light. The first beam splitter 11a
and the second beam splitter 11b are so set that the p-polarization for
the first beam splitter 11a is the s-polarization for the second beam
splitter 11b and that the s-polarization for the first beam splitter 11a
is the p-polarization for the second beam splitter 11b.

[0074]Light transmitted by the second beam splitter 11b is detected by a
first optical intensity detector 11c and light reflected by the second
beam splitter 11b is detected by a second optical intensity detector 11d.
Outputs from the first optical intensity detector 11c and from the second
optical intensity detector 11d are supplied respectively to a controller
(not shown). The controller actuates the quarter-wave plate 4a, half-wave
plate 4b, and depolarizer 4c constituting the polarization state
converter 4, according to need.

[0075]In the first beam splitter 11a and the second beam splitter 11b, as
described above, the reflectance for the p-polarization is substantially
different from the reflectance for the s-polarization. In the
polarization monitor 11, therefore, the reflected light from the first
beam splitter 11a includes, for example, an s-polarization component
(which is an s-polarization component for the first beam splitter 11a but
p-polarization component for the second beam splitter 11b) which is
approximately 10% of incident light to the first beam splitter 11a, and,
for example, a p-polarization component (which is a p-polarization
component for the first beam splitter 11a but s-polarization component
for the second beam splitter 11b) which is approximately 1% of incident
light to the first beam splitter 11a.

[0076]The reflected light from the second beam splitter 11b includes, for
example, a p-polarization component (which is a p-polarization component
for the first beam splitter 11a but s-polarization component for the
second beam splitter 11b) which is approximately 10%×1%=0.1% of
incident light to the first beam splitter 11a, and, for example, an
s-polarization component (which is an s-polarization component for the
first beam splitter 11a but p-polarization component for the second beam
splitter 11b) which is approximately 1%×10%=0.1% of incident light
to the first beam splitter 11a.

[0077]In the polarization monitor 11, as described above, the first beam
splitter 11a has the function of extracting reflected light in a
polarization state different from a polarization state of incident light,
from the optical path in accordance with its reflection characteristic.
In consequence, the polarization monitor 11 is able to detect the
polarization state (degree of polarization) of incident light to the
first beam splitter 11a and thus the polarization state of illumination
light to the mask M, based on the output of the first optical intensity
detector 11c (information about the intensity of transmitted light from
the second beam splitter 11b, i.e., information about the intensity of
light in much the same polarization state as the reflected light from the
first beam splitter 11a), though slightly affected by variation in
polarization due to the polarization characteristic of the second beam
splitter 11b.

[0078]In addition, the polarization monitor 11 is so set that the
p-polarization for the first beam splitter 11a is the s-polarization for
the second beam splitter 11b and that the s-polarization for the first
beam splitter 11a is the p-polarization for the second beam splitter 11b.
As a result, the polarization monitor 11 is able to detect the quantity
(intensity) of incident light to the first beam splitter 11a and thus the
quantity of illumination light to the mask M, without substantially being
affected by change in the polarization state of incident light to the
first beam splitter 11a, based on the output of the second optical
intensity detector 11d (information about the intensity of the light
successively reflected by the first beam splitter 11a and the second beam
splitter 11b).

[0079]The polarization monitor 11 is used in this manner to detect the
polarization state of incident light to the first beam splitter 11a and
thus to determine whether the illumination light to the mask M is in a
desired unpolarized state, linear polarization state, or circular
polarization state. When the controller confirms that the illumination
light to the mask M (and thus to the wafer W) is not in the desired
unpolarized state, linear polarization state, or circular polarization
state, based on the result of the detection by the polarization monitor
11, it actuates and adjusts the quarter-wave plate 4a, half-wave plate
4b, and depolarizer 4c constituting the polarization state converter 4 to
adjust the state of the illumination light to the mask M to the desired
unpolarized state, linear polarization state, or circular polarization
state.

[0080]When a diffractive optical element for quadrupole illumination (not
shown) is set in the illumination optical path, instead of the
diffractive optical element 5 for annular illumination, it can effect
quadrupole illumination. The diffractive optical element for quadrupole
illumination has the following function: when a parallel light beam
having a rectangular cross section is incident thereto, it forms an
optical intensity distribution of quadrupole shape in its far field.
Therefore, a light beam having passed through the diffractive optical
element for quadrupole illumination forms an illumination field of
quadrupole shape consisting of four circular illumination fields around
the optical axis AX, for example, on the incidence surface of the micro
fly's eye lens 10. As a result, a secondary light source of the same
quadrupole shape as the illumination field formed on the incidence
surface is also formed on the rear focal plane of the micro fly's eye
lens 10.

[0081]When a diffractive optical element for circular illumination (not
shown) is set in the illumination optical path, instead of the
diffractive optical element 5 for annular illumination, it can effect
normal circular illumination. The diffractive optical element for
circular illumination has the following function: when a parallel light
beam having a rectangular cross section is incident thereto, it forms an
optical intensity distribution of circular shape in the far field.
Therefore, a light beam having passed through the diffractive optical
element for circular illumination forms an illumination field of circular
shape consisting of a circular illumination field around the optical axis
AX, for example, on the incidence surface of the micro fly's eye lens 10.
As a result, the secondary light source of the same circular shape as the
illumination field formed on the incidence surface is also formed on the
rear focal plane of the micro fly's eye lens 10.

[0082]Furthermore, when another diffractive optical element for multi-pole
illumination (not shown) is set in the illumination optical path, instead
of the diffractive optical element 5 for annular illumination, it is
feasible to implement one of various multi-pole illuminations (dipole
illumination, octupole illumination, etc.). When the diffractive optical
element 5 for annular illumination is replaced by a diffractive optical
element (not shown) for forming an optical intensity distribution of an
annular shape having an annular ratio different from that of the
diffractive optical element 5, in its far field as set in the
illumination optical path, it can expand the varying range of the annular
ratio. Similarly, when the diffractive optical element 5 for annular
illumination is replaced by a diffractive optical element with an
appropriate characteristic (not shown) as set in the illumination optical
path, it becomes feasible to implement one of illuminations of various
forms.

[0083]FIG. 5 is a drawing schematically showing a major configuration of
the exposure apparatus according to the present embodiment, and shows a
configuration from the mask blind to the wafer. With reference to FIG. 5,
the exposure apparatus of the present embodiment is so arranged that a
birefringent element 21 is located in the optical path between the mask
blind 13 and the imaging optical system 14 and that an optical rotator 22
is located at a predetermined position in the optical path of the imaging
optical system 14. The present embodiment achieves a nearly azimuthal
polarization state in a lens aperture of an optical system (a combined
optical system of the illumination optical system (2-14) with the
projection optical system PL) through collaboration of the birefringent
element 21 and the optical rotator 22.

[0084]The general action of the birefringent element 21 and optical
rotator 22, i.e., the basic principle of the present invention will be
described below. In the present invention, linear polarization of
circumferential vibration in the lens aperture of the optical system is
defined as azimuthal polarization as shown in FIG. 6(a), and linear
polarization of radial vibration in the lens aperture as radial
polarization as shown in FIG. 6(b). In this case, coherency of two rays
on the image plane in the optical system having a large image-side
numerical aperture is higher in azimuthal polarization than in radial
polarization. Therefore, when the polarization state of light in the lens
aperture is set to a nearly azimuthal polarization state, a high-contrast
object image can be obtained on the image plane.

[0085]In the present invention, therefore, in order to realize the nearly
azimuthal polarization state in the lens aperture, as shown in FIG. 7,
the birefringent element 21 and optical rotator 22 are provided at
predetermined positions in the optical path of the optical system which
is telecentric on the object side, for example. The birefringent element
21 is, for example, an optically transparent member of a plane-parallel
plate shape made of a uniaxial crystal like rock crystal, and the
crystallographic axis thereof is arranged in parallel with the optical
axis AX. In this case, when a light beam of spherical waves is made
incident to the birefringent element 21 made of a positive uniaxial
crystal, a circumferential distribution around the optical axis AX is
obtained as a fast axis distribution in the lens aperture of the optical
system, as shown in FIG. 8(a).

[0086]On the other hand, if a light beam of spherical waves is made
incident to the birefringent element 21 made of a negative uniaxial
crystal, a radial distribution around the optical axis AX is obtained as
a fast axis distribution in the lens aperture of the optical system, as
shown in FIG. 8(b). Let us suppose herein that a light beam of spherical
waves in a circular polarization state having a polarization distribution
in the lens aperture as shown in FIG. 9 is made incident to the
birefringent element 21. Then the light beam having passed through the
birefringent element 21 comes to have a polarization distribution in the
lens aperture as shown in FIG. 10(a) or (b).

[0087]The polarization distribution shown in FIG. 10(a) is obtained when
clockwise circularly polarized light as shown in FIG. 9 is made incident
to the birefringent element 21 corresponding to the fast axis
distribution of FIG. 8(a), i.e., the birefringent element 21 made of a
positive uniaxial crystal. On the other hand, the polarization
distribution shown in FIG. 10(b) is obtained when clockwise circularly
polarized light as shown in FIG. 9 is made incident to the birefringent
element 21 corresponding to the fast axis distribution of FIG. 8(b),
i.e., the birefringent element 21 made of a negative uniaxial crystal.

[0088]The optical rotator 22 is, for example, an optically transparent
member of a plane-parallel plate shape made of an optical material with
optical rotatory power like rock crystal, and is located behind the
birefringent element 21 (on the image side). The optical rotator 22 is
arranged so that the crystallographic axis thereof is parallel to the
optical axis AX, and has a function of rotating a polarization state in a
lens aperture by a predetermined angle according to a thickness thereof,
an angle of incidence of a light beam, or the like. In the present
invention, the polarization state of the light beam having passed through
the birefringent element 21 is rotated by 45° (i.e., the
polarization state in the lens aperture is rotated by 45°) by the
action of the optical rotator 22, to obtain a polarization distribution
in the lens aperture as shown in FIG. 11.

[0089]However, where the birefringent element 21 is one made of a positive
uniaxial crystal, the birefringent element 21 provides the polarization
distribution shown in FIG. 10(a) and it is thus necessary to use the
optical rotator 22 made of an optical material with counterclockwise
optical rotatory power in order to obtain the polarization distribution
in the lens aperture as shown in FIG. 11. On the other hand, where the
birefringent element 21 is one made of a negative uniaxial crystal, the
birefringent element 21 provides the polarization distribution shown in
FIG. 10(b) and it is thus necessary to use the optical rotator 22 made of
an optical material with clockwise optical rotatory power in order to
obtain the polarization distribution in the lens aperture as shown in
FIG. 11.

[0090]It is seen with reference to the polarization distribution in the
lens aperture shown in FIG. 11 that a ray passing the center (optical
axis AX) of the lens aperture is in a circular polarization state,
polarization states vary from an elliptic polarization state to a linear
polarization state toward the periphery of the aperture, and the
polarization states are distributed with rotational symmetry with respect
to the optical axis AX. In the polarization distribution in the lens
aperture shown in FIG. 11, as described above, the azimuthal polarization
state (linear polarization state of circumferential vibration around the
optical axis AX) is not achieved throughout the whole area in the lens
aperture, but the azimuthal polarization state is achieved at least in
the peripheral region of the lens aperture.

[0091]When consideration is given to the fact that degradation of
coherency in formation of image is greater for rays in the peripheral
region of the lens aperture than for rays in the central region of the
lens aperture, the polarization distribution in which the azimuthal
polarization state is achieved in the peripheral region of the lens
aperture as shown in FIG. 11 is approximately equivalent to the
polarization distribution in which the azimuthal polarization state is
achieved throughout the whole area of the lens aperture as shown in FIG.
6(a), in terms of improvement in the contrast of the object image. In the
present invention, as described above, the nearly azimuthal polarization
state in the lens aperture can be realized through collaboration of the
birefringent element 21 and optical rotator 22, whereby the high-contrast
object image can be obtained eventually on the image plane. In the
polarization distribution in the lens aperture shown in FIG. 11, the
azimuthal polarization state is achieved in the outermost peripheral
region of the lens aperture, but the region in the lens aperture where
the azimuthal polarization state is achieved does not have to be limited
to the outermost periphery. The region can be appropriately set according
to need. When the polarization distribution where the azimuthal
polarization state is achieved in the peripheral region of the lens
aperture as shown in FIG. 11 is combined with the annular illumination or
multi-pole illumination such as dipole or quadrupole illumination, the
polarization distribution in the illumination light beam turns into a
nearly azimuthal polarization state and thus a higher-contrast object
image can be obtained on the image plane.

[0092]The birefringent element can be an optically transparent member made
of an appropriate optical material except for rock crystal, e.g., an
optical material with linear birefringence such as MgF2 or
LiCaAlF6 (lithium calcium aluminum fluoride). In another potential
example, the birefringent element is, for example, a pair of optically
transparent members made of a crystal material of the cubic system like
fluorite, and the pair of optically transparent members are positioned so
that the fast axis distribution in the lens aperture becomes a nearly
circumferential distribution or a nearly radial distribution.

[0093]Specifically, the birefringent element can be a pair of optically
transparent members arranged in a state in which the crystal orientation
<111> is parallel to the optical axis and in which the other
crystal orientations are relatively rotated by about 60° around
the optical axis. In this case, when a light beam of spherical waves is
made incident to the birefringent element consisting of the pair of
optically transparent members, a circumferential distribution about the
optical axis AX is obtained as the fast axis distribution in the lens
aperture of the optical system as shown in FIG. 8(a), just as in the case
of the birefringent element made of a positive uniaxial crystal.
Accordingly, when a light beam of spherical waves is made incident in a
clockwise circular polarization state as shown in FIG. 9, the
polarization distribution in the lens aperture as shown in FIG. 10(a) is
obtained.

[0094]The birefringent element can also be a pair of optically transparent
members arranged in a state in which the crystal orientation <100>
is approximately parallel to the optical axis and in which the other
crystal orientations are relatively rotated by about 45° around
the optical axis. In this case, when a light beam of spherical waves is
made incident to the birefringent element consisting of the pair of
optically transparent members, a radial distribution around the optical
axis AX is obtained as the fast axis distribution in the lens aperture of
the optical system as shown in FIG. 8(b), just as in the case of the
birefringent element made of a negative uniaxial crystal. Therefore, when
a light beam of spherical waves is made incident in a clockwise circular
polarization state as shown in FIG. 9, the polarization distribution in
the lens aperture as shown in FIG. 10(b) is obtained.

[0095]The birefringent element made of the uniaxial crystal, and the
birefringent element consisting of the pair of optically transparent
members made of the crystal material of the cubic system are elements in
which the amount of birefringence varies according to angles of
incidence. Therefore, when a light beam of spherical waves is made
incident, the birefringent element functions as one having the fast axis
distribution as shown in FIG. 8(a) or (b), to obtain the polarization
distribution in the lens aperture as shown in FIG. 10(a) or (b). For
making the polarization distribution in the lens aperture approximately
uniform in the plane, as shown in FIG. 7, it is preferable to place the
birefringent element of a uniaxial crystal (or the birefringent element
consisting of the pair of optically transparent members) 21 in an
approximately telecentric optical path.

[0096]On the other hand, the optical rotator 22 preferably uniformly
rotates the polarization state in the lens aperture. Therefore, the
optical rotator 22 is preferably located at a position where there is
little variation in the angle of incidence of the light beam, as shown in
FIG. 7. Specifically, the optical rotator 22 is preferably located at a
position where the light beam is incident with variation of not more than
10° in the angle of incidence, and the optical rotator 22 is more
preferably located at a position where the light beam is incident with
variation of not more than 7° in the angle of incidence. Besides
rock crystal, the optical rotator 22 can be made of an appropriate
optical material with optical rotatory power.

[0097]Referring again to FIG. 5, the exposure apparatus of the present
embodiment is arranged so that the birefringent element of an optically
transparent member made of a uniaxial crystal, for example, like rock
crystal (or the birefringent element consisting of a pair of optically
transparent members made of a crystal material of the cubic system, for
example, like fluorite) 21 is located in the optical path between the
mask blind 13 and the imaging optical system 14, i.e., in the nearly
telecentric optical path near the mask blind 13 located at the position
optically conjugate with the mask M being a surface to be illuminated. In
addition, the optical rotator 22, for example, made of rock crystal is
located at the position where the light beam is incident, for example,
with variation of not more than 10° in the angle of incidence, in
the optical path of the imaging optical system 14.

[0098]In this state, when the half-wave plate 4b and depolarizer 4c both
are retracted from the illumination optical path and when the
crystallographic axis of the quarter-wave plate 4a is set at a
predetermined angle relative to incident elliptically polarized light, a
light beam of nearly spherical waves is incident in a circular
polarization state to the birefringent element 21. As a result, the
present embodiment is able to achieve the nearly azimuthal polarization
state in the lens aperture while suppressing the loss of light quantity,
based on the simple configuration, through collaboration of the
birefringent element 21 for achieving the nearly circumferential
distribution or the nearly radial distribution as the fast axis
distribution in the lens aperture, and the optical rotator 22 disposed
behind it and adapted to rotate the polarization state in the lens
aperture. Therefore, the present embodiment is able to form the
high-contrast image of the microscopic pattern of the mask M on the wafer
W to effect high-throughput and faithful exposure.

[0099]FIG. 12 is a drawing schematically showing a major configuration of
an exposure apparatus according to a first modification example of the
present embodiment. In the first modification example, the configuration
from the mask blind 13 to the wafer W is similar to that in the
embodiment shown in FIG. 5. However, the first modification example is
different from the embodiment shown in FIG. 5, in that the birefringent
element 21 is located in the optical path between the imaging optical
system 14 and the mask M and in that the optical rotator 22 is located at
a predetermined position in the optical path of the projection optical
system PL.

[0100]Namely, in the first modification example the birefringent element
21 is located in the nearly telecentric optical path near the mask M, in
the optical path of the illumination optical system (2-14). Furthermore,
the optical rotator 22 is located at a position relatively close to the
mask M in the optical path of the projection optical system PL, e.g., at
a position where the light beam is incident with variation of not more
than 10° in the angle of incidence. As a result, the first
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through collaboration
of the birefringent element 21 and the optical rotator 22 as the
embodiment of FIG. 5 was.

[0101]FIG. 13 is a drawing schematically showing a major configuration of
an exposure apparatus according to a second modification example of the
present embodiment. In the second modification example, just as in the
first modification example, the configuration from the mask blind 13 to
the wafer W is similar to that in the embodiment shown in FIG. 5.
However, the second modification example is different from the embodiment
shown in FIG. 5, in that the birefringent element 21 is located in the
optical path between the mask M and the projection optical system PL and
in that the optical rotator 22 is located at a predetermined position in
the optical path of the projection optical system PL.

[0102]Namely, in the second modification example the birefringent element
21 is located in the nearly telecentric optical path near the mask M, in
the optical path of the projection optical system PL. Furthermore, the
optical rotator 22 is located at a position relatively close to the mask
M in the optical path of the projection optical system PL, e.g., at a
position where the light beam is incident with variation of not more than
10° in the angle of incidence. As a result, the second
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through collaboration
of the birefringent element 21 and the optical rotator 22 as the
embodiment of FIG. 5 was.

[0103]FIG. 14 is a drawing schematically showing a major configuration of
an exposure apparatus according to a third modification example of the
present embodiment. In the third modification example, just as in the
first modification example and the second modification example, the
configuration from the mask blind 13 to the wafer W is similar to that in
the embodiment shown in FIG. 5.

[0104]However, the third modification example is different from the
embodiment shown in FIG. 5, in that the birefringent element 21 is
located in the optical path between the mask M and the projection optical
system PL and in that the optical rotator 22 is located at a
predetermined position in the optical path of the projection optical
system PL.

[0105]Namely, in the third modification example, as in the second
modification example, the birefringent element 21 is located in the
nearly telecentric optical path near the mask M (i.e., in the optical
path nearly telecentric on the mask M side), in the optical path of the
projection optical system PL. However, different from the second
modification example, the optical rotator 22 is located at a position
relatively close to the wafer W in the optical path of the projection
optical system PL, e.g., at a position where the light beam is incident
with variation of not more than 10° in the angle of incidence. As
a result, the third modification example is also able to achieve the
nearly azimuthal polarization state in the lens aperture while
suppressing the loss of light quantity, based on the simple
configuration, through collaboration of the birefringent element 21 and
the optical rotator 22 as the embodiment shown in FIG. 5 was.

[0106]FIG. 15 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fourth modification example of the
present embodiment. In the fourth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the embodiment
shown in FIG. 5. However, the fourth modification example is different
from the embodiment of FIG. 5 in that, while the projection optical
system PL in the embodiment of FIG. 5 is a dioptric system, the
projection optical system PL of the fourth modification example is a
catadioptric system of a threefold imaging type including a concave
mirror CM. The fourth modification example is also different from the
embodiment shown in FIG. 5, in that the birefringent element 21 is
located in the optical path between the imaging optical system 14 and the
mask M and in that the optical rotator 22 is located at a predetermined
position in the optical path of the projection optical system PL.

[0107]Namely, in the fourth modification example the birefringent element
21 is located in the nearly telecentric optical path near the mask M, in
the optical path of the illumination optical system (2-14). Furthermore,
the optical rotator 22 is located at a position relatively close to the
mask M in an optical path of a first imaging optical system G1 in the
projection optical system PL, e.g., at a position where the light beam is
incident with variation of not more than 10° in the angle of
incidence. As a result, the fourth modification example is also able to
achieve the nearly azimuthal polarization state in the lens aperture
while suppressing the loss of light quantity, based on the simple
configuration, through collaboration of the birefringent element 21 and
the optical rotator 22 as the embodiment of FIG. 5 was.

[0108]FIG. 16 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fifth modification example of the
present embodiment. In the fifth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the fourth
modification example of FIG. 15. However, the fifth modification example
is different from the fourth modification example of FIG. 15 in that the
birefringent element 21 is located in the optical path between the mask M
and the projection optical system PL and in that the optical rotator 22
is located at a predetermined position in the optical path of the
projection optical system PL.

[0109]Namely, in the fifth modification example the birefringent element
21 is located in the nearly telecentric optical path near the mask

[0110]M (i.e., in the optical path nearly telecentric on the mask M side),
in the optical path of the projection optical system PL. Furthermore, the
optical rotator 22 is located at a position relatively close to the wafer
W in the optical path of the first imaging optical system G1 in the
projection optical system PL, e.g., at a position where the light beam is
incident with variation of not more than 10° in the angle of
incidence. As a result, the fifth modification example is also able to
achieve the nearly azimuthal polarization state in the lens aperture
while suppressing the loss of light quantity, based on the simple
configuration, through collaboration of the birefringent element 21 and
the optical rotator 22 as the fourth modification example was.

[0111]FIG. 17 is a drawing schematically showing a major configuration of
an exposure apparatus according to a sixth modification example of the
present embodiment. In the sixth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the fourth
modification example of FIG. 15. However, the sixth modification example
is different from the fourth modification example of FIG. 15 in that the
birefringent element 21 and the optical rotator 22 both are located at
predetermined positions in the optical path of the projection optical
system PL.

[0112]Namely, in the sixth modification example the birefringent element
21 is located at a position optically conjugate with the mask M (i.e., at
a position where a secondary image of mask M is formed) or in a nearly
telecentric optical path near the conjugate position, in an optical path
between a second imaging optical system G2 and a third imaging optical
system G3. Furthermore, the optical rotator 22 is located at a position
relatively close to the wafer W in an optical path of the third imaging
optical system G3 of the projection optical system PL, e.g., at a
position where the light beam is incident with variation of not more than
10° in the angle of incidence. As a result, the sixth modification
example is also able to achieve the nearly azimuthal polarization state
in the lens aperture while suppressing the loss of light quantity, based
on the simple configuration, through collaboration of the birefringent
element 21 and the optical rotator 22 as the fourth modification example
was. In the sixth modification example the birefringent element 21 is
located in the optical path on the wafer W side with respect to the
optical path folding mirror in the projection optical system PL. In the
case of this configuration, even if there occurs a phase difference due
to reflection between the p-polarization and the s-polarization for the
optical path folding mirror, the polarization state after the reflection
can be nearly circular polarization when the polarization state impinging
upon the optical path folding mirror is elliptic polarization. Therefore,
the sixth modification example is more preferably adopted than the
aforementioned fifth modification example in the case where the optical
path folding mirror is located in the projection optical system.

[0113]In the embodiment of FIG. 5 and in the first modification example to
the sixth modification example, the birefringent element 21 is an
optically transparent member made of a uniaxial crystal, for example,
like rock crystal or a pair of optically transparent members made of a
crystal material of the cubic system, for example, like fluorite.
However, the birefringent element does not have to be limited to those,
but the birefringent element can also be an optically transparent member
with internal stress substantially with rotational symmetry with respect
to the optical axis, e.g., an optically transparent member like a
plane-parallel plate of silica.

[0114]In this case, when a light beam of plane waves in a substantially
circular polarization state is made incident to the birefringent element
consisting of the optically transparent member with internal stress
substantially which is rotational symmetry with respect to the optical
axis, the polarization distribution in the lens aperture as shown in FIG.
10(a) or (b) can be obtained. For making the polarization distribution in
the lens aperture approximately uniform in the plane, the birefringent
element consisting of the optically transparent member with internal
stress is preferably located near the pupil of the optical system (in the
embodiment of FIG. 5, for example, a position near the pupil of the
imaging optical system 14 and closer to the light source than the optical
rotator 22). Concerning the details of a method of providing the
optically transparent member, for example, like the plane-parallel plate
of silica with the substantially rotationally symmetric internal stress
(to provide the member with a desired birefringence distribution),
reference can be made, for example, to International Application
Published under PCT WO03/007045 and the corresponding U.S. Pat. No.
6,788,389. The teachings of U.S. Pat. No. 6,788,389 are hereby
incorporated by reference.

[0115]In the embodiment of FIG. 5 and in the first modification example to
the sixth modification example, the nearly azimuthal polarization state
in the lens aperture is achieved through collaboration of the two
elements disposed with a spacing, i.e., the birefringent element 21 and
the optical rotator 22. However, the nearly azimuthal polarization state
in the lens aperture can also be achieved by using a birefringent optical
rotator which is made of an optical material with linear birefringence
and optical rotatory power and the optic axis of which is arranged
substantially in parallel with the optical axis, e.g., a birefringent
optical rotator consisting of an optically transparent member of a
plane-parallel plate shape made of rock crystal, and making a light beam
in a substantially circular polarization state incident to the
birefringent optical rotator.

[0116]In this case, the birefringent optical rotator is located at a
position where a light beam of substantially spherical waves is incident
thereto, and has a required thickness for converting a light beam in a
peripheral region of incident light into a light beam in a substantially
linear polarization state of approximately circumferential vibration in
the lens aperture. Namely, the relationship between the thickness of the
birefringent optical rotator and angles of incident rays is so set that
circularly polarized rays incident to the peripheral region of the
birefringent optical rotator are converted into linearly polarized light
by birefringence and that their polarization is rotated by 45° by
optical rotatory power.

[0117]The change of polarization in the birefringent optical rotator will
be described below with reference to the Poincare sphere shown in FIG.
18. In FIG. 18, S1, S2, and S3 are the Stokes parameters
to indicate a polarization state. In the birefringent optical rotator,
light incident in a perfectly circular polarization state corresponding
to point A (0,0,1) is subject to rotational action around the S1
axis due to the birefringence and subject to rotational action around the
S3 axis due to the optical rotatory power, to reach a azimuthal
polarization state corresponding to point B (1,0,0).

[0118]Incidentally, in the case of the aforementioned birefringent element
21, the light incident in a perfectly circular polarization state
corresponding to point A (0,0,1) is subject to only rotational action
around the S1 axis due to the birefringence, to reach point B'
(0,1,0). For adjusting the amount of the rotation and the amount of the
birefringence in the birefringent optical rotator, the birefringent
optical rotator is preferably comprised of a first optically transparent
member made of an optical material with clockwise optical rotatory power
(e.g., right-handed rock crystal), and a second optically transparent
member made of an optical material with counterclockwise optical rotatory
power (e.g., left-handed rock crystal).

[0119]FIG. 19 is a drawing schematically showing a major configuration of
an exposure apparatus according to a seventh modification example of the
present embodiment. In the seventh modification example the configuration
from the mask blind 13 to the mask M is similar to that in the embodiment
shown in FIG. 5. However, the seventh modification example is different
from the embodiment shown in FIG. 5, in that the birefringent element 21
and the optical rotator 22 are replaced by a birefringent optical rotator
23 disposed in the optical path between the mask blind 13 and the imaging
optical system 14.

[0120]Namely, in the seventh modification example the birefringent optical
rotator 23 is located in the nearly telecentric optical path near the
mask blind 13 located at the position optically conjugate with the mask M
being a surface to be illuminated, in the optical path of the
illumination optical system (2-14). As a result, the seventh modification
example is also able to achieve the nearly azimuthal polarization state
in the lens aperture while suppressing the loss of light quantity, based
on the simple configuration, through the action of the birefringent
optical rotator 23 as the embodiment of FIG. 5 was.

[0121]FIG. 20 is a drawing schematically showing a major configuration of
an exposure apparatus according to an eighth modification example of the
present embodiment. In the eighth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the seventh
modification example of FIG. 19. However, the eighth modification example
is different from the seventh modification example in that the
birefringent optical rotator 23 is located in the optical path between
the imaging optical system 14 and the mask M. Namely, in the eighth
modification example the birefringent optical rotator 23 is located in
the nearly telecentric optical path near the mask M, in the optical path
of the illumination optical system (2-14). As a result, the eighth
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through the action of
the birefringent optical rotator 23 as the seventh modification example
was.

[0122]FIG. 21 is a drawing schematically showing a major configuration of
an exposure apparatus according to a ninth modification example of the
present embodiment. In the ninth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the seventh
modification example of FIG. 19. However, the ninth modification example
is different from the seventh modification example in that the
birefringent optical rotator 23 is located in the optical path between
the mask M and the projection optical system PL. Namely, in the ninth
modification example the birefringent optical rotator 23 is located in
the nearly telecentric optical path near the mask M (i.e., in the optical
path nearly telecentric on the mask M side), in the optical path of the
projection optical system PL. As a result, the ninth modification example
is also able to achieve the nearly azimuthal polarization state in the
lens aperture while suppressing the loss of light quantity, based on the
simple configuration, through the action of the birefringent optical
rotator 23 as the seventh modification example was.

[0123]FIG. 22 is a drawing schematically showing a major configuration of
an exposure apparatus according to a tenth modification example of the
present embodiment. In the tenth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the seventh
modification example of FIG. 19. However, the tenth modification example
is different from the seventh modification example in that the
birefringent optical rotator 23 is located in the optical path between
the projection optical system PL and the wafer W. Namely, in the tenth
modification example the birefringent optical rotator 23 is located in
the nearly telecentric optical path near the wafer W (i.e., in the
optical path nearly telecentric on the wafer W side), in the optical path
of the projection optical system PL. As a result, the tenth modification
example is also able to achieve the nearly azimuthal polarization state
in the lens aperture while suppressing the loss of light quantity, based
on the simple configuration, through the action of the birefringent
optical rotator 23 as the seventh modification example was.

[0124]FIG. 23 is a drawing schematically showing a major configuration of
an exposure apparatus according to an eleventh modification example of
the present embodiment. In the eleventh modification example the
configuration from the mask blind 13 to the mask M is similar to that in
the fourth modification example of FIG. 15. However, the eleventh
modification example is different from the fourth modification example in
that the birefringent element 21 and the optical rotator 22 are replaced
by a birefringent optical rotator 23 located in the optical path between
the imaging optical system 14 and the mask M. Namely, in the eleventh
modification example the birefringent optical rotator 23 is located in
the nearly telecentric optical path near the mask M, in the optical path
of the illumination optical system (2-14). As a result, the eleventh
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through the action of
the birefringent optical rotator 23 as the fourth modification example
was.

[0125]FIG. 24 is a drawing schematically showing a major configuration of
an exposure apparatus according to a twelfth modification example of the
present embodiment. In the twelfth modification example the configuration
from the mask blind 13 to the mask M is similar to that in the eleventh
modification example of FIG. 23. In the twelfth modification example the
birefringent optical rotator 23 is located at a position optically
conjugate with the mask M (a position where a secondary image of mask M
is formed) or in a nearly telecentric optical path near the conjugate
position, in the optical path between the second imaging optical system
G2 and the third imaging optical system G3. As a result, the twelfth
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through the action of
the birefringent optical rotator 23 as the eleventh modification example
was.

[0126]FIG. 25 is a drawing schematically showing a major configuration of
an exposure apparatus according to a thirteenth modification example of
the present embodiment. In the thirteenth modification example the
configuration from the mask blind 13 to the mask M is similar to that in
the eleventh modification example of FIG. 23. However, the thirteenth
modification example is different from the eleventh modification example
in that the birefringent optical rotator 23 is located in the optical
path between the projection optical system PL and the wafer W. Namely, in
the thirteenth modification example the birefringent optical rotator 23
is located in a nearly telecentric optical path near the wafer W (i.e.,
in an optical path nearly telecentric on the wafer W side), in the
optical path of the projection optical system PL. As a result, the
thirteenth modification example is also able to achieve the nearly
azimuthal polarization state in the lens aperture while suppressing the
loss of light quantity, based on the simple configuration, through the
action of the birefringent optical rotator 23 as the eleventh
modification example was. In the twelfth modification example and the
thirteenth modification example, the birefringent optical rotator 23 is
located in the optical path on the wafer W side with respect to the
optical path folding mirror in the projection optical system PL. In the
case of this configuration, as in the case of the aforementioned sixth
modification example, even if there occurs a phase difference due to
reflection between the p-polarization and the s-polarization for the
optical path folding mirror, the polarization state after the reflection
can be nearly circular polarization when the polarization state impinging
upon the optical path folding mirror is set to elliptic polarization.
Therefore, the thirteenth modification example is more preferably adopted
than the aforementioned eleventh modification example in the case where
the optical path folding mirror is located in the projection optical
system.

[0127]FIG. 26 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fourteenth modification example of
the present embodiment. In the fourteenth modification example the
configuration from the mask blind 13 to the mask M is similar to that in
the embodiment shown in FIG. 25. However, the fourteenth modification
example is different from the exposure apparatus of the embodiment of
FIG. 25 in that, while the mask M is illuminated by circularly polarized
light in the exposure apparatus of the embodiment of FIG. 25, the mask M
is illuminated by linearly polarized light in the exposure apparatus of
the fourteenth modification example and in that, while the projection
optical system PL of the embodiment of FIG. 25 is a catadioptric optical
system of the threefold imaging type including the concave mirror CM and
two optical path folding mirrors, the projection optical system PL of the
fourteenth modification example is a catadioptric optical system of a
twofold imaging type including a concave mirror CM, a polarization beam
splitter PBS, and one optical path folding mirror FM.

[0128]In FIG. 26, the projection optical system PL in the fourteenth
modification example is an optical system telecentric on the mask M side
and on the wafer W side, and is comprised of a first imaging optical
system G1 for forming an intermediate image of mask M and a second
imaging optical system G2 for forming an image of this intermediate image
on a wafer W as a photosensitive substrate.

[0129]The first imaging optical system G1 is comprised of a first lens
unit located nearest to the mask side (mask-side field lens unit), a
polarization beam splitter PBS for reflecting a light beam of linearly
polarized light having passed through the first lens unit, a first
quarter-wave plate QW1 for converting the light beam of linearly
polarized light reflected by the polarization beam splitter PBS, into a
light beam of circularly polarized light, a concave mirror CM for
reflecting the light beam having passed through the first quarter-wave
plate QW1, a negative lens unit located in the optical path between the
concave mirror CM and the first quarter-wave plate QW1, a second
quarter-wave plate QW2 for converting the light beam of linearly
polarized light transmitted via the negative lens unit and the first
quarter-wave plate by the polarization beam splitter PBS, into a light
beam of circularly polarized light, a optical path folding mirror FM for
deflecting the optical path of the light beam from the polarization beam
splitter PBS by about 90°, and a positive lens unit located
between the polarization beam splitter PBS and the intermediate image
point (intermediate-image-side field lens unit). This
intermediate-image-side field lens unit keeps the optical path on the
intermediate image side of the first imaging optical system G1 (the
optical path between the first imaging optical system G1 and the second
imaging optical system G2) approximately telecentric.

[0130]The second imaging optical system G2 has a structure similar to the
dioptric projection optical system PL in the fourth modification example
shown in FIG. 14, in which the birefringent element 21 is located in the
optical path between the second imaging optical system G2 and the
intermediate image point and in which the optical rotator 22 is located
at a predetermined position in the optical path of the second imaging
optical system G2, preferably, at a position near an aperture stop AS.

[0131]Then the linearly polarized light from the mask M passes through the
first lens unit, is then reflected by the polarization beam splitter PBS,
and thereafter travels through the first quarter-wave plate QW1 to be
converted into circularly polarized light, and the circularly polarized
light travels through the negative lens unit to reach the concave mirror
CM. The light beam of circularly polarized light reflected by the concave
mirror CM travels again through the negative lens unit, and then passes
through the first quarter-wave plate QW1 to be converted into linearly
polarized light, and the linearly polarized light passes through the
polarization beam splitter PBS to reach the second quarter-wave plate
QW2. This light beam is converted into circularly polarized light by the
second quarter-wave plate QW2, and then the linearly polarized light is
reflected by the optical path folding mirror FM and travels through the
positive lens unit being the intermediate-image-side field lens unit, to
form an intermediate image of the mask M. Light from this intermediate
image then travels through the birefringent element 21 to be incident to
the second imaging optical system G2, and thereafter passes through the
optical rotator 22 in this second imaging optical system G2 to form a
reduced image as a secondary image of the mask M on the image plane. This
reduced image is a mirror image of the mask M (which is an image having a
negative lateral magnification in the direction in the plane of the
drawing and a positive lateral magnification in the direction normal to
the plane of the drawing).

[0132]In the fourteenth modification example the birefringent element 21
is located in the nearly telecentric optical path near the intermediate
image point, in the optical path of the projection optical system PL.
Furthermore, the optical rotator 22 is located near the pupil position of
the projection optical system PL. As a result, the fourteenth
modification example is also able to achieve the nearly azimuthal
polarization state in the lens aperture while suppressing the loss of
light quantity, based on the simple configuration, through collaboration
of the birefringent element 21 and the optical rotator 22 as the
embodiment of FIG. 25 was.

[0133]In the fourteenth modification example, the illumination optical
system may be arranged to illuminate the mask M with circularly polarized
light and in this case, a third quarter-wave plate is located in the
optical path between the mask M and the polarization beam splitter PBS in
the projection optical system PL so as to guide linearly polarized light
to the polarization beam splitter. In the fourteenth modification example
the polarization beam splitter PBS is arranged to reflect the light beam
from the mask M, but the polarization beam splitter PBS may be arranged
to transmit the light beam from the mask M (so that the optical system
from the mask M to the concave mirror CM is aligned on a straight line).

[0134]FIG. 27 is a drawing schematically showing a major configuration of
an exposure apparatus according to a fifteenth modification example of
the present embodiment. In the fifteenth modification example the
configuration from the mask blind 13 to the mask M and the configuration
from the intermediate image point to the wafer W are similar to those in
the embodiment (fourteenth modification example) shown in FIG. 26.
However, the fifteenth modification example is different from the
fourteenth modification example in that, while the projection optical
system PL of the fourteenth modification example is arranged to guide the
light beam from the mask M to the wafer W while reflecting it three
times, the projection optical system PL of the fifteenth modification
example is arranged to guide the light beam from the mask M to the wafer
W while reflecting it four times.

[0135]In FIG. 27, the projection optical system PL in the fifteenth
modification example is an optical system telecentric on the mask M side
and on the wafer W side as the projection optical system PL in the
fourteenth modification example was, and is comprised of a first imaging
optical system G1 for forming an intermediate image of the mask M, and a
second imaging optical system G2 for forming an image of this
intermediate image on the wafer W as a photosensitive substrate.

[0136]The first imaging optical system G1 is comprised of a first lens
unit located nearest to the mask side (mask-side field lens unit), a
polarization beam splitter PBS having a first polarization splitting
surface PBS1 for reflecting a light beam of linearly polarized light
having passed through the first lens unit, a first quarter-wave plate QW1
for converting the light beam of linearly polarized light reflected by
the first polarization splitting surface PBS1, into a light beam of
circularly polarized light, a concave mirror CM for reflecting the light
beam having passed through the first quarter-wave plate QW1, a negative
lens unit located in the optical path between the concave minor CM and
the first quarter-wave plate QW1, a second polarization splitting surface
PBS2 for transmitting a light beam of linearly polarized light
transmitted via the negative lens unit and the first quarter-wave plate
by the first polarization splitting surface PBS1, a second quarter-wave
plate QW2 for converting the light beam of linearly polarized light
transmitted by the second polarization splitting surface PBS2, into a
light beam of circularly polarized light, a return mirror RM having a
reflecting plane for returning the light beam of circularly polarized
light from the second quarter-wave plate QW2, a third quarter-wave plate
QW3 for converting a light beam of linearly polarized light reflected by
the second polarization splitting surface PBS2 after the round-trip
passage through the second quarter-wave plate QW2, into a light beam of
circularly polarized light, and a positive lens unit
(intermediate-image-side field lens unit) located between the second
polarization splitting surface PBS2 and the intermediate image point.
This intermediate-image-side field lens unit keeps the optical path on
the intermediate image side of the first imaging optical system G1 (the
optical path between the first imaging optical system G1 and the second
imaging optical system G2) nearly telecentric.

[0137]The second imaging optical system G2 has a structure similar to the
catadioptric projection optical system PL in the fourteenth modification
example shown in FIG. 26, in which the birefringent element 21 is located
in the optical path between the second imaging optical system G2 and the
intermediate image point and in which the optical rotator 22 is located
at a predetermined position in the optical path of the second imaging
optical system G2, preferably, at a position near an aperture stop AS.

[0138]The light beam of linearly polarized light from the mask M travels
through the first lens unit, is then reflected by the first polarization
splitting surface PBS1 of the polarization beam splitter PBS, and then
travels through the first quarter-wave plate QW1 to be converted into
circularly polarized light, and the circularly polarized light travels
through the negative lens unit to reach the concave mirror CM. The light
beam of circularly polarized light reflected by the concave mirror CM
travels again through the negative lens unit and thereafter passes
through the first quarter-wave plate QW1 to be converted into linearly
polarized light. The linearly polarized light passes through the first
polarization splitting surface PBS1 and the second polarization splitting
surface PBS2 of the polarization beam splitter PBS to reach the second
quarter-wave plate QW2. This light beam is converted into circularly
polarized light by the second quarter-wave plate QW2, and the circularly
polarized light then reaches the return mirror RM. The light beam of
circularly polarized light reflected by the return mirror RM travels
through the second quarter-wave plate QW2 to be converted into linearly
polarized light, and then the linearly polarized light is reflected by
the second polarization splitting surface PBS2 of the polarization beam
splitter PBS to reach the third quarter-wave plate QW3. The light beam of
linearly polarized light incident to the third quarter-wave plate QW3 is
converted into a light beam of circularly polarized light by this third
quarter-wave plate QW3, and the light beam of circularly polarized light
then travels through the positive lens unit being the
intermediate-image-side field lens unit, to form an intermediate image of
the mask M. Light from this intermediate image travels through the
birefringent element 21 to be incident to the second imaging optical
system G2, and then passes through the optical rotator in this second
imaging optical system G2 to form a reduced image as a secondary image of
the mask M on the image plane. This reduced image is a front image of the
mask M (an image having a positive lateral magnification in the direction
in the plane of the drawing and a positive lateral magnification in the
direction perpendicular to the plane of the drawing, i.e., an erect
image).

[0139]In the fifteenth modification example the birefringent element 21 is
also located in the nearly telecentric optical path near the intermediate
image point, in the optical path of the projection optical system PL.
Furthermore, the optical rotator 22 is located near the pupil position of
the projection optical system PL. As a result, the fifteenth modification
example is able to achieve the nearly azimuthal polarization state in the
lens aperture while suppressing the loss of light quantity, based on the
simple configuration, through collaboration of the birefringent element
21 and the optical rotator 22 as the embodiment of FIG. 26 was.

[0140]In the fifteenth modification example the illumination optical
system may be arranged to illuminate the mask M with circularly polarized
light and in this case, the fourth quarter-wave plate may be located in
the optical path between the mask M and the polarization beam splitter
PBS in the projection optical system PL so as to guide linearly polarized
light to the polarization beam splitter PBS. The fifteenth modification
example is arranged to reflect the light beam from the mask M by the
first polarization splitting surface PBS1 of the polarization beam
splitter PBS, but the optical system may be arranged so that the light
beam from the mask M is transmitted by the first polarization splitting
surface PBS1 (so that the optical system from the mask M to the concave
mirror CM is aligned on a straight line). In the fifteenth modification
example the second polarization splitting surface PBS2 of the
polarization beam splitter PBS is arranged to reflect the light beam from
the return mirror RM, but the optical system may also be arranged so that
the second polarization splitting surface PBS2 transmits the light beam
from the return mirror (so that the optical system from the return mirror
RM to the wafer W is aligned on a straight line). At this time, the light
beam from the first polarization splitting surface PBS1 is reflected by
the second polarization splitting surface PBS2.

[0141]The following controls may be properly performed according to the
shape of the pattern as an exposed object on the mask M: the control of
the polarization state by the polarization state converter 4, the control
of the exchange operation of the diffractive optical element, and the
control of the operation of the axicon system 8 as an annular ratio
changing means as described above. It is contemplated in the
above-described embodiment and modification examples that when the
polarization state is set to the linear polarization state or the
unpolarized state through the action of the polarization state converter
4, the polarization state is affected by the birefringent element 21 or
the birefringent optical rotator 23 disposed in the optical path between
the mask M and the wafer W. In that case, the birefringent element 21 or
the birefringent optical rotator 23 may be retracted from the optical
path, or the birefringent element 21 or the birefringent optical rotator
23 may be replaced with an optically transparent member without
birefringence (e.g., a plane-parallel plate made of silica or the like)
as occasion may demand. Such retracting operation or replacing operation
of the birefringent element 21 or the birefringent optical rotator 23 may
also be controlled in synchronism with the aforementioned controls.

[0142]The exposure apparatus of the aforementioned embodiment can be used
to fabricate micro devices (semiconductor devices, image pickup devices,
liquid-crystal display devices, thin-film magnetic heads, etc.) by
illuminating a mask (reticle) by the illumination optical apparatus
(illumination block) and projecting a pattern to be transferred, formed
in the mask, onto a photosensitive substrate with the projection optical
system (exposure block). An example of a technique of forming a
predetermined circuit pattern in a wafer or the like as a photosensitive
substrate with the exposure apparatus of the aforementioned embodiment to
obtain semiconductor devices as micro devices will be described below
with reference to the flowchart of FIG. 28.

[0143]The first block 301 in FIG. 28 is to deposit a metal film on each
wafer in one lot. The next block 302 is to apply a photoresist onto the
metal film on each wafer in the lot. The subsequent block 303 is to
sequentially transfer an image of a pattern on the mask into each shot
area on each wafer in the lot through the projection optical system,
using the exposure apparatus of the aforementioned embodiment. The
subsequent block 304 is to perform development of the photoresist on each
wafer in the lot and the subsequent block 305 is to perform etching on
each wafer in the lot, using the resist pattern as a mask and thereby to
form a circuit pattern corresponding to the pattern on the mask, in each
shot area on each wafer. Subsequent blocks include formation of circuit
patterns in upper layers, and others, thereby fabricating devices such as
semiconductor devices. The above-described semiconductor device
fabrication method permits us to obtain semiconductor devices with
extremely fine circuit patterns at high throughput.

[0144]The exposure apparatus of the aforementioned embodiment can also be
used to fabricate a liquid-crystal display device as a micro device by
forming predetermined patterns (circuit pattern, electrode pattern, etc.)
on plates (glass substrates). An example of a technique for fabricating
the liquid-crystal display device will be described below with reference
to the flowchart of FIG. 29. In FIG. 29, a pattern forming block 401 is
to execute a so-called photolithography block to transfer a pattern of a
mask onto a photosensitive substrate (glass substrate coated with a
resist, or the like) with the exposure apparatus of the aforementioned
embodiment. This photolithography block results in forming the
predetermined pattern including a number of electrodes and others on the
photosensitive substrate. Thereafter, the exposed substrate is subjected
to each of blocks such as development, etching, and resist removal,
whereby a predetermined pattern is formed on the substrate. Thereafter,
the process transfers to next color filter forming block 402.

[0145]The next color filter forming block 402 is to form a color filter in
which a number of sets of three dots corresponding to R (Red), G (Green),
and B (Blue) are arrayed in a matrix pattern, or in which sets of three
stripe filters of R, G, and B are arrayed as a plurality of lines along
the horizontal scan line direction. After completion of the color filter
forming block 402, a cell assembling block 403 is carried out. The cell
assembling block 403 is to assemble a liquid crystal panel (liquid
crystal cell), using the substrate with the predetermined pattern
obtained in the pattern forming block 401, the color filter obtained in
the color filter forming block 402, and so on.

[0146]In the cell assembling block 403, for example, a liquid crystal is
poured into between the substrate with the predetermined pattern obtained
in the pattern forming block 401 and the color filter obtained in the
color filter forming block 402, to fabricate a liquid crystal panel
(liquid crystal cell). The subsequent module assembling block 404 is to
install each of components such as an electric circuit, a backlight, etc.
for display operation of the assembled liquid crystal panel (liquid
crystal cell) to complete the liquid-crystal display device. The
above-described method of fabricating the liquid-crystal display device
permits us to obtain the liquid-crystal display device with an extremely
fine circuit pattern at high throughput.

[0147]In the aforementioned embodiment the exposure light was the KrF
excimer laser light (wavelength: 248 nm) or the ArF excimer laser light
(wavelength: 193 nm), but, without having to be limited to this, the
present invention can also be applied to the other appropriate laser
light sources, e.g., an F2 laser light source for supplying laser
light of wavelength of 157 nm. Furthermore, the aforementioned embodiment
described the present invention with the example of the exposure
apparatus provided with the illumination optical apparatus, but it is
apparent that the present invention can be applied to the ordinary
illumination optical apparatus for illuminating a surface to be
illuminated, except for the masks and wafers.

[0148]In the aforementioned embodiment, it is also possible to adopt a
technique of filling the optical path between the projection optical
system and the photosensitive substrate with a medium having the
refractive index of more than 1.1 (typically, a liquid), i.e., the
so-called liquid immersion method. When the liquid fills the space
between the projection optical system and the photosensitive material
such as the resist applied on the surface of the photosensitive
substrate, the transmittance on the resist surface becomes higher for
diffracted light of the s-polarization component (TE polarization
component) contributing to improvement in contrast than when air (gas)
fills the space between the projection optical system and the resist
applied on the surface of the photosensitive substrate; therefore, high
imaging performance can be achieved even if the numerical aperture NA of
the projection optical system is over 1.0. In this case, the technique of
filling the liquid in the optical path between the projection optical
system and the photosensitive substrate can be one selected from the
method of locally filling the space with the liquid as disclosed in
International Publication WO99/49504, the method of moving a stage
holding a substrate as an exposed object, in a liquid bath as disclosed
in Japanese Patent Application Laid-Open No. 6-124873, the method of
forming a liquid bath of a predetermined depth on a stage and holding a
substrate in the liquid bath as disclosed in Japanese Patent Application
Laid-Open No. 10-303114, and so on. The teachings of International
Publication WO99/49504, Japanese Patent Application Laid-Open No.
6-124873, and Japanese Patent Application Laid-Open No. 10-303114 are
hereby incorporated by reference.

[0149]The liquid is preferably one that is transparent to exposure light,
that has the refractive index as high as possible, and that is stable
against the projection optical system and the photoresist applied on the
surface of the substrate; for example, where the KrF excimer laser light
or the ArF excimer laser light is used as exposure light, the liquid can
be pure water or deionized water. Where the exposure light is the F2
laser light, the liquid can be a fluorine-based liquid, for example, such
as fluorine oil or perfluoro polyether (PFPE) capable of transmitting the
F2 laser light. The present invention is also applicable to
twin-stage type exposure apparatus. The structure and exposure operation
of the twin-stage type exposure apparatus are disclosed, for example, in
Japanese Patent Applications Laid-Open No. 10-163099 and Laid-Open No.
10-214783 (corresponding to U.S. Pat. No. 6,341,007, U.S. Pat. No.
6,400,441, U.S. Pat. No. 6,549,269, and U.S. Pat. No. 6,590,634),
Published Japanese translation of PCT Application No. 2000-505958
(corresponding to U.S. Pat. No. 5,969,441), or U.S. Pat. No. 6,208,407.
The teachings of U.S. Pat. Nos. 6,341,007, 6,400,441, 6,549,269,
6,590,634, 5,969,441, and 6,208,407 are hereby incorporated by reference.

[0150]The invention is not limited to the fore going embodiments but
various changes and modifications of its components may be made without
departing from the scope of the present invention. Also, the components
disclosed in the embodiments may be assembled in any combination for
embodying the present invention. For example, some of the components may
be omitted from all components disclosed in the embodiments. Further,
components in different embodiments may be appropriately combined.